diff --git a/lib/low_balance.rb b/lib/low_balance.rb
index 41bbdd8639cc50fa894cde4811ea7882c1163b48..a02445975e951fdbcea9f24f6be2565de58247ef 100644
--- a/lib/low_balance.rb
+++ b/lib/low_balance.rb
@@ -8,10 +8,10 @@ class LowBalance
 		return Locked.new unless customer.registered?
 
 		ExpiringLock.new(
-			"jmp_customer_low_balance-#{customer.customer_id}",
+			"jmp_customer_low_balance-#{customer.billing_customer_id}",
 			expiry: 60 * 60 * 24 * 7
 		).with(-> { Locked.new }) do
-			for_no_lock(customer)
+			customer.billing_customer.then(&method(:for_no_lock))
 		end
 	end